Ibudilast (Ketas) Treatment of Tinnitus.

Factors influencing the degree of annoyance caused by tinnitus and the clinical effectiveness of ibudilast (Ketase) in the treatment of tinnitus were analyzed in 43 patients complaining of persistent tinnitus.1) Multiple regression analysis demonstrated that the degree of annoyance caused by tinnitus tended to be worsened by the awareness of hearing loss (p<0.05), persistence of tinnitus (p=0.08) or presence of a middle ear lesion (p=0.12). Discriminant analysis showed that the critical limit of hearing at 2 kHz was 32.6 dBHL for an awareness of hearing loss.2) At 2 weeks 64.5% and at 4 weeks 61.9% of the 43 patients treated with ibudilast reported some improvement in the degree of annoyance caused by tinnitus. In 19.4% (2 weeks) and in 33.3% (4 weeks), respectively, the improvement was marked.3) Multiple regression analysis of the subjective improvement of tinnitus 1, 2, 4, 6 and 8 weeks after the beginning of ibudilast medication indicated that advanced age (critical age 65.2 years, p<0.05), high tone loss (p<0.05) and variety of tinnitus (p<0.01) were correlated with subjective improvement. On the other hand, the presence of a middle ear lesion (p<0.05), vestibular symptoms (p<0.05) and bilaterality of tinnitus (p<0.05) were factors which prevented subjective improvement with ibudilast therapy. These results indicate that ibudilast is effective, especially for elderly patients complaining of tinnitus and for those with tinnitus and high tone hearing loss.4) No severe side effects were noted in this study.